Sand tubes are used to increase the amount of friction between a railroad track and the wheel of a train. Sand tubes are located at the front of a wheel and disperse sand along the track to allow greater friction during cold and icy weather between the wheel of the train and track. Sand tubes without heating systems require manually hitting the sand tube to break up the ice inside the tube. This can cause severe damage to the sand tube rendering the sand tube inoperable. United States Federal Regulations require that all trains to have sand tubes operable at all times and there is a significant fine if the tubes are frozen when inspected.
Typical prior art such as that shown in U.S. Pat. No. 1,528,552 implement heating systems for keeping the sand inside the sand tubes above freezing temperature to ensure that the sand is not frozen during operation. The prior art disclosed in U.S. Pat. No. 1,528,552 implements an electrical heated medium coiled around the lower portion of the sand tube. The electrical heated medium is then encased in a structure. The structure is then filled with a loose fire retardant material such as asbestos.
The prior art in U.S. Pat. No. 1,528,552 has disadvantages and difficulties in implementing an efficient and properly functioning sand tube. The heating element is not in constant connection to the sand tube, therefore does not efficiently heat the sand inside of the tube. Additionally, the structure surrounding the heating element is difficult to maintain when repairs are needed.
Another such prior art reference U.S. Pat. No. 2,654,622 discloses a heating system which uses hot liquid traveling through coils wrapped around the sand tube and forced air provided by the locomotive to keep the sand from freezing and to keep the sand dispensing tube freely operable. This invention has difficulties and disadvantages in that the heating coils do not rise to a sufficient heat temperature to keep the sand from freezing during very low temperatures. Therefore, even with such methods of heating the sand, the sand tube can still freeze where the hot water inside the coils does not sufficiently heat the sand inside of the tube.
Other methods of heating the sand inside the tube include using engine exhaust, heat provided off of the engine, or other circulated heated liquids. However, these methods fail to properly heat the sand to an adequate temperature during extreme cold.